Fuel pump drive for diesel engines



Nov. 30, 1948. R. H. SHEPPARD FUEL PUMP DRIVE FOR DIESEL ENGINES 2Sheets-Sheet 1 Filed July 9, 1946 -ld X Nov. 30, 1948. R. H. SHEPPARD 12,455,275

FUEL PUMP DRIVE FOR DIESEL ENGINES Filed July e, 1946 2 Sheets-Sheet 2 IPatented Nov. '30, 1948 UNITED STATES PATENT OFFICE 2,455,275 FUEL PUMPDRIVE FOR DIESEL ENGINES Richard H. Sheppard, Hanover, Pa. ApplicationJuly 9, 1946, Serial No. 682,398

4 Claims.

This invention relates to the starting of Diesel motors and has for itsprincipal object the provision of a mechanism which will insure that thefuel is delivered to the combustion chamber of the Diesel engine at agreater speed than would be had if the starter were directly connectedto the fuel pump shaft. As a corollary the invention includes theprovision of a spring member in the chain of gearing between the crankshaft of the engine and its fuel pump shaft, particularly one in whichpower is stored in-the spring during a portion of the revolution of thelarge starting gear and when the spring is released a sharp motion orimpulse is given to the fuel pump shaft whereby the fuel is dischargedin nearer accord with the manner in which fuel is discharged while theengine is under load.

A still further object of the invention consists in the insertion in 9,Diesel engine starting mechanism of a quick impulse device which wil1automatically become inoperative as soon as the engine approaches normalspeed.

In the drawings:

Figure 1 is an elevation.

Figure 2 is a vertical section through the axis of the fuel pump shaft.

Figure 3 is a section on line 33 of Figure 1.

Figure 4 is a section on line 5-3 of Figure 1.

Figure 5 is a section on line 5-5 of Figure 4.

Figure 6 is an elevation of the cup.

Figure 7 is a detail on line l'l of Figure 4.

The fuel pump shaft of the sists, as is usual, of an inner member Illand an outer member Ii, which, while they have relative movement, as faras the present invention is concerned, may be considered as a. singlemember. In any event, the two members invariably rotate together. Theouter member turns in a bushing i2 in the fuel pump casing i 3 andcarries at its end a screw member i5 secured to the fuel pump shaft asby the bolts l 6. This extension i5 of the fuel pump shaft turns in abushing ll between the screw extension and the timing device plate l9,which itself is fast to the large bushing or hearing secured as by thebolts 2| to the back wall 22 of the gear case. 5

The member'20 has the usual oil hole 23 and the usual oil outlet 25 andthe forward extension, that is, to the left in Figure 2, of the bushing20, furnishes a bearing as at 26 for the hollow hub 21 of the gear 28which receives power from the crank shaft 30 through an idler 3 7 A cup33 is permanently secured as by the rivets It to a plate 36 fittingsnugly the gear 28 and fast to it as by the .bolts 31.

Diesel engine con-' A retaining nut 39 presame radius as the outside ofvents movement of the gear 28, the plate and the cup 33, away from thefuel pump shaft.

The forward portion 40 of the) screw member I5 which maybe considered asa part of the fuel pump shaft is slabbed off to afford a seat for thefloating washer 4| which fits the stub shaft portion 40, rather snugly,the latter being threaded at its free end to receive the nut 39.

The small washer 36 turns freely on the stub shaft and its function isto prevent too great movement of the pawl 60.

A spring 50 is anchored at one end as at 5i to the washer 4| whichalways turns with the fuel pump shaft. At its other and larger end thespring 50 is anchored as at 52 to an extending portion 53 of the cup 53.As best seen in Figure 4, the cylindrical flange of the cup is cut awayon both sides leaving two extensions 53. The purpose of these twooppositely disposed members 53 is to wind the spring and to release thespring. Within the cup is a driven plate 55 which generally is circular,but has two portions 56 of greater radius and just clearing the insidewall of the flange cup and having its outside arc of exactly the thecup. The driven plate 55 may therefore have relative movement ofrotation with respect to the cup from one edge 5! of an extension 53 tothe adjacent edge 53 of the opposite flange extension 53. A pawl 63 ispivoted as at '6! to the driven plate 55. The larger end 62 of the pawlacts as a weight and holds the shorter arm 63 of the pawl so that itextends beyond the outer mangin of the cup 33. A small point 63 on thepawl is merely for convenfence in restoring the pawl to operativeposition I when the centrifugal force of rotation throws the heavy arm62 outward against the inner wall of the flange extension 53 at whichtime of course the short arm 63 is well within the cup. A fixed spacer65 is mounted on the plate 55 to extend exactly the same distance as thetop of the pivot pin 6| the better to position the real thin washer 67.

A stud 66 is fixed to the timing plate i9 so as to be engaged by theshort arm 53 of the pawl as the driven plate 55 rotates. The engagementof the pawl and the stud hold the driven plate against movement andsince this driven plate has no relative movement with respect to thefuel pump shaft the latter is held stationary as long as the pawlengages the stop. The driving cup, however, is continuously rotated incounter clockwise direction as seen in Figure 4 and in time the leadingedge 58 will make contact withthe now stationary pawl and will camtheshort end 63 inwardly. The release of this short end of the lowing edge51 of the flange extension 53 of the cup. The net result of this actionis to give far greater speed of rotation to the fuel pump shaft thanwould be had if the drive from the crank shaft were constant. Hence,while the fuel discharge is in perfect timing there is in everyrevolution of the fuel pump shaft one sharp impulse per cylinder andthis results in a far more desirable discharge of Diesel fuel to thecombustion chamber. Due to the centrifugal eflect on the pawl theimpulse ceases just as soon as engine gets up to normal speedas at suchtime the larger end 62 of the pawl is thrown outward with the point 64in engagement with the inner surface of the flange extension 53 of thecup 35.

'Except for the point there would be a danger of the pawl wedgingagainst the cup flange.

I claim:

1. In a device to facilitate the starting of 8. Diesel engine, a fuelpump shaft, a gear coaxial therewith and adapted to be driven from thecrank shaft of the engine, mechanism for connecting the gear with theshaft including a spring connection, means for winding thespring as thegear turns without rotating the shaft, and trip means for releasing thewound spring to rotate the shaft at a higher rate of rotation than thegear after the gear has rotated through a chosen angle of movement, saidtrip means including a centrifugally controlled member whereby thewinding device is rendered inoperative when the gear reaches a chosenspeed of rotation.

2. The device of claim 1 in which a plate fast to the shaft carries apawl which at slow speeds engages a stop, and the gear carries a cup,the spring is fast to the cup at one end and to the shaft at the otherend, and a projection on the cup cams the pawl from the stop and freesthe plate and shaft so that the spring now wound rotates the shaft.

3. In a device for facilitating the starting of a Diesel engine, acasing, a fuel pump shaft journaled in said casing, a stop fixed to thecasing. a plate fast to the shaft and having two extending ears, a pawlpivoted to the plate and having one end movable into engagement with thestop at slow speeds of the plate, a cup coaxial with the shaft andhaving a flange partly cut away to provide an opening to receive the twoears and the pawl with lost motion in excess of 45, a spring fast at oneend to the cup and connected at the other end to the shaft, means forrotating the cup in timed sequence with the engine shaft, whereby thefuel pump shaft, which is held against movement while the pawl engagesthe stop and the cup winds the spring, is driven at a more rapidrotation than that of the cup by the transfer of stored power in thespring when the flange cams the pawl from the stop, thus freeing theshaft and permitting the spring to unwind.

4. In a device for facilitating the starting of a Diesel engine, a fuelpump shaft, 9. gear rotating in fixed relation to the engine shaft, andmeans for transferring power from the gear to the fuel pump shaftincluding a spring connection alternately wound and released, to give aseries of quick impulse movements to the fuel pump shaft while theengine is being started, whereby in starting the engine, the fuel isdelivered at a greater speed than if the fuel pump shaft were directlyconnected to the gear, and thus the fuel is delivered in starting insharp impulses corresponding more nearly to the manner in which the fuelis delivered while the engine is under load.

RICHARD H. SHEPPARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,394,938 Schmidt et a1. Feb. 12,1946 FOREIGN PATENTS Number Country Date 505,014 Great Britain May 5,1939

